Vibration dampeners or shock absorbers for drilling applications are well known in the art. However, vibration dampener or shock absorbers for both longitudinal and rotary shock loads have been characterized by short operating lives.
Work U.S. Pat. No. 4,109,488 discloses a shock absorbing rotary drive coupling having a drive shaft and a driven shaft with an annular rubber torque transmitting member.
Garrett U.S. Pat. No. 3,779,040 discloses a vibration dampener having a drive shaft and a driven shaft with a plurality of rubber torque transmitting members sandwiched between steel drive plates on the respective members. This product is available commercially as the Smith "SWIVEL MOUNT SHOCK SUB".
Hughes U.S. Pat. Nos. 3,257,827 and 3,306,078 disclose rotary drilling shock absorbers having a drive shaft and a driven shaft with a plurality of rubber torque transmitting members sandwiched between steel drive plates on the respective members.
Vertson U.S. Pat. No. 3,323,326 discloses a well drilling shock absorber having a drive shaft and a driven shaft with helical ribs and splines therein and rubber torque transmitting members therebetween.
Taciuk U.S. Pat. No. 3,746,330 discloses a drill stem shock absorber having a drive shaft and a driven shaft with a plurality of rubber torque transmitting members sandwiched between annular steel drive plates on the respective members.
Neimark U.S. Pat. No. 3,947,009 discloses a drill stem shock absorber having a drive shaft and a driven shaft with a plurality of rubber torque transmitting members sandwiched between annular steel drive plates on the respective members, the plates being secured together by metal pins and bolts.
Alther U.S. Pat. No. 4,139,994 discloses a vibration isolator having a drive shaft and a driven shaft with torque transmitting splines having elastic material sandwiched therebetween and separate longitudinal load absorbing members tapered to give a predetermined load displacement curve and preloaded in an amount equal to the expected set in the members.
Hansen U.S. Pat. No. 4,571,215 discloses a vibration dampener apparatus having a drive shaft and a driven shaft with torque transmitting splines having elastic material sandwiched therebetween and a separate longitudinal load absorbing member.
This invention is distinguished from the prior art by providing a longitudinal and rotary shock absorber for rotary and percussion drill bits comprising a drive shaft and a driven shaft interconnected by separated longitudinal and torque load absorbing members. One of the shafts has internal drive plates or splines which fit inside cavities on the other shaft and rubber shock absorbing members absorbing rotary torque and extension shock loads. An annular rubber shock absorbing member is positioned in a cavity between the shafts to absorb longitudinal compression shock loads. The isolation of the torque shock absorbing function from the longitudinal shock absorbing function improves the life of the tool considerably.